EarthLink SuperCookie: a follow-up

Regarding our previous report of EarthLink's Custom Browser Token, a couple of readers suggest that the "SuperCookie" is not as benign as the quoted article suggested. For example, "if you do a Google search on one of the ID numbers (user-agent string) obtained, you can view a list of web sites visited by that particular computer." "The user-agent string has the purpose of tracking user adoption and traffic. It can be used for other purposes as well (collecting data). The user-agent string tags browser users across the entire web in server web logs." (Thanks, David Crandon and Ken Kashmarek.)